Gate generator



J. M. LESTER ET AL 2,537,065

GATE GENERATOR Jan. 9, 1951 Filed April 18, 1944 I I I l 4M. 'FX S J-E-Q J R W/L KER-SON TTO RN EY Patented Jan. 9, 1951 UNITED STATES PATENT OFFl-CE 37,065" GENER-Nroit john tester-,1, acr ue Centre, anti wreath R1 Wilkerson, Eay's lda-N. Y as'signor's' to The spar? camera-non, a constraint (stoneware ApplicatiomApril B; 1944;- Serial N6: 531,598" 4 claims; (01. '2Kt 27') This invention relates to; electronic circuitsg generally, and concerns itselfmore particularly with apparatus for generating gating voltages or gates. I g

We are aware that it-has been proposed previously to produce gating voltages; or gates; by generating a train of Waves in a tuned. circuit,- and shaping the gate from a one-half cycle pulse o'fthe wave train by clippingandamplifying the same.

By a novel circuit arrangement we havefound' it possible to greatly reduce the number of elements in this typeof gate generator'andto improve the form of the gate produced. 7

Accordingly, it is an' object of the present invention to provide an improved" gate producing. circuit.

Another' object of the present invention lies in the provision of a compact and economical gate producing device.

It is a further object of the present'invention to provide a gateipro'duc'ing" circuit havingia re duced number of electron discharge device's.

Another object is to provide" a gate pro'duc ing circuit'cha'racterize'd by non-regeneration be tween the elements'ther'eof. v

Another object or the" invention is to" pro vide a gate'generator"which will produce'a' pulsle' by absorbing all but the first negativehalf-cycle of a wave train set up in a resonant circuit, and will subsequently clip and amplify the pulse to for'r'ri a gate.

It is another object'of't'heinvention to arran" a circuit in which the natural frequency of'an" V oscillating element may be varied to form a variable wave train, portions of which are" aloe" sorbed to form a pulse which is subsequently" clipped and amplified to form a variable width ate;

A' still further object or the invention is the arrangement of a' circuit for producing'v'ariable gates ranging froma pulse in the order of a frac" tion of a microsecond toa widegate, insom'eiii' stances exceeding several hundred microsecondsi Yet another olojectof thefinvention is the arrangement of an electronic discharge element ina gate; generating circuit such that'saidele ment will perform a plurality of functions including those'of a unilateral current-conducting" element and a clipping and amplifying devicei Another object of the invention is'to prov de a gate generator circuit which contains a minimum nu'r'nber of circuit elements and which is especially adaptable to apparatus installed in air-borne equipment.

These andother objects; of the; invention willbecome apparent; astheg description proceeds. Incarrying out our invention in agpreferredembodimentthereofl wehave arranged in a" gate generator circuit-a; single envelope electronic discha-rgedevice', such as a; twin triode, whose dual elements pepforjin the functions; a switching tube}: a unilateral. current-conducting element, and a clipping. anj amplifying tage. For the: purpose orproa'qeinga waterfall, or a voltage oscillation; we ave connected the cathode lead of tl'iel-i lfof tHe'tuBea tuned" circuit in men the oscillations" ar dvoped". 'rfi" second half of the" electronic discharge device is cont-teet rs reciveth'is" estimating voltage, and" y th'pejriodjof'ithe pulsefr iiiwhi fi ag e w tness is d lf 'hi'c jal-representatiofi o'fthe van: ous vo age: waveiorriis app'ear-ing at indicated points in he 'c'ircufit'PiiluZstratiecl in Fig;- l. g

' oft'he invention illustrated in Fig.

elop'e, elect'rmin'ic discharge device ni i 156- df the" twin trio'de' type,- is" v in the function of generating a wave tfain in thefiis't Half memo r-rem pulse s' talehwhic issiib'seliuent rid amplified in tli ecohd half of the tiilSe"to"prc'i'd1'ic'e agate? A sq-iiare wav et siiitilil form is impressed upon input terr niri'al- H of the circuit and deliv first half of tube 0 which ac sasa singleti'iode I3 C6iip1iiig elements j'conifirisiiig agiid capabi for" 14 anda g ficlneak resist-or l5} are pro vidd in -the grld circuit Of elme'nt [3. Plate It of tliis element receives positive'* energy from source I! and its cathode l9 has=connected between: it and ground=an-' inductance coil20 which togetherxwith a capacitor It forms a resonant circuit 22':

For the purpose of varying the period of oscillations set up in this tuned circuit 22, a variable impedance comprising a capacitor 23 and a variable resistor 24 may be connected across the tuned circuit 22 by means of a switch 25.

The second half of tube H], which may also be considered as a single triode 2B, acts as a rectifier and a clipping and amplifying device. Its grid 21 is connected to cathode I9 of the element i3 and its plate 28 receives positive energy from source ll through a plate resistor 29. Across this resistor the desired gating voltage is developed for delivery to output terminal 30. Cathode 3l is connected to ground, as shown.

When a pulse, such as 32, of the input voltage A (Fig. 2) is received on the grid l2, and at time t1, grid i2 is driven positive and grid current fiows through the resistor 15. This action charges the grid side of capacitor l4 negatively to some fixed value. Under this action element I3 is rendered conducting and plate current and grid current fiow through the inductance coil 20. At time 132, grid l2 goes negative, element 13 is rendered non-conducting, and its plate current is cut off. Since the time rate of change of current flow is large, a negative pulse appears across the inductance coil and oscillations are set up in the tuned circuit 22. If left undisturbed circuit branch 22 would continue to oscillate at its resonant frequency, but by the action Of element 26 it is permitted to oscillate for one-half cycle only. As soon as the wave goes positive with respect to ground, grid 21 is driven positive with respect to its cathode 3| annd grid current begins to flow. This action tends to load the resonant circuit 22 causing it to stop oscillating at the termination of the first negative half-cycle, and a pulse such as 33 in voltage B (Fig. 2) is formed. This pulse which appears on grid 21 is then clipped and amplified by element 26 to produce the gate 34 in wave 0, Fig. 2. Thus, pulse 33 carries element 26 beyond cut off, which clips it as illustrated in the figure and the voltage at terminal goes up to the level of source l1. As grid 2'! is driven positive by pulse 33, the tube is again rendered conducting and the voltage at 30 goes down. Accordingly a voltage C is developed across resistor 29, which gives the desired gate 34. In this manner element 26 of tube In operates both as a diode and a triode, thereby eliminating a number of circuit components.

It will be noted that a small pip 35 appears in voltage B, which in the output voltage C, forms the pip 35. The presence of this slight distortion in the wave is due to the action of the leading edge of the pulse 32. Since the inductance coil 20 provides a small amount of resistance there is a slight IR drop across it which accounts for this small pulse. Its amplitude is very slight, however, and it does not present an objectionable condition in most uses of the circuit. However, if a, particular use of the circuit should require its elimination, it may be removed by passing the output of the circuit through a biased cathode follower.

It will be noted that the circuit of Fig. 1 is suitable for producing a suitable gate with the circuit constituted of only two electron discharge devices, such as triodes I3, 26. In addition, the circuit is characterized by non-regeneration between the triodes I3, 26.

There are no critical values for any of the circuit parameters and the limitations placed on the selection of apparatus elements are few. The

inductance coil 20 should be chosen with as high a Q as possible, so that a pulse will appear across it only at a time when plate current is out 01f in element 13. Also, the input voltage A, Fig. 2, should be of sufiicient period, that is, the time between t1 and t2 should be of such duration that the first half of tube I0 will not be rendered conducting and non-conducting in such a short time that oscillations are not set up in the tuned circuit 22.

It is apparent that many changes could be made in the above construction and many apparently widely different embodiments of this invention could be made without departing from the scope thereof. By way of example, a variable impedance, as previously indicated, may be connected across the tuned circuit 22 to vary the period of oscillation set up therein. Accordingly, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

What is claimed is:

1. In a gate generator, a first electronic discharge device having grid, anode and cathode electrodes, a high-Q resonant circuit connected in the cathode lead of said discharge device, means for connecting said anode electrode to a positive energy source, means for connecting said grid electrode to receive a square wave voltage under the influence of which said first discharge device becomes operable to set up voltage oscillations in said resonant circuit thereby to produce a wave train, a second electronic discharge device having grid, anode and cathode electrodes, means for operatively connecting said grid electrode of said second electronic discharge device to said resonant circuit, and means for connecting the electrodes of said second electronic discharge device to operate as a rectifier and a clipping and amplifying stage, said first and second electron discharge devices being the only discharge devices in said generator, and said first and second devices being characterized by non-regeneration therebetween, whereby a pulse is formed from the first negative half-cycle of said oscillating voltage and said pulse is subsequently clipped and amplified to generate a gate.

2. In a gate producing circuit, a first electron discharge device having first grid, anode and cathode electrodes, mean for producing a wave train, said wave train producing means including a high-Q resonant circuit connected in the cathode lead of said first discharge device, means for connecting said anode electrode of said first discharge device to a positive energy source, means for terminating current conduction of said first electron discharge device including means for connecting said first grid electrode to receive a square-wave voltage, a second electron discharge device having second grid, anode and cathode electrodes, said second grid being connected directly to said first cathode, and means for connecting said second electrode for clipping and amplifying the first negative half-cycle of said oscillating voltage of said resonant circuit, said first and second discharge devices being characterized by non-regenerative action therebetween, whereby a clipped and amplified gate is generated.

3. A driven gate generator comprising first and second electron discharge devices, said first electron discharge device having first anode and cathode electrodes and only one control grid, 2.

high Q resonant wavetrain producing circuit connected in the cathode lead of said first discharge device, means for setting up voltage oscillations in said resonant circuit including means for connecting said one control grid to receive a control pulse to terminate the flow of current in said first electron discharge device; said second electron discharge device having second grid, anode and cathode electrodes; means for connecting said second grid electrode to said resonant circuit, and means for connecting all of said second electrodes to operate as a clipping and amplifying stage, said first and second electron discharge devices constituting the only electron discharge devices in said generator, and said first and second electron discharge devices being characterized by non-regenerative action therebetween, whereby a pulse is formed from the first negative half-cycle of said oscillating voltage and said pulse is subsequently clipped and amplified to generate a gate.

4. Apparatus as in claim 3 wherein the frequency of said resonant circuit is adjustable, comprising a series connected variable resistor and condenser shunting said resonant circuit.

JOHN M. LESTER. JEFFERSON R. WILKERSON.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,760,957 Ohl June 3, 1930 1,908,249 Hund May 9, 1933 2,063,025 Blumlein Dec. 8, 1936 2,097,334 Bowman-Manifold Oct. 26, 1937 2,103,090 Plebanski Dec. 21, 1937 2,153,202 Nichols Apr. 4, 1939 2,181,309 Andrieu Nov. 28, 1939 2,208,422 Hugon July 14, 1940 2,226,459 Bingley Dec. 24, 1940 2,237,661 Ernst Apr. 8, 1941 2,266,668 Tubs Dec. 16, 1941 2,277,000 Bingley Mar. 17, 1942 2,408,061 Grieg Sept. 24, 1946 2,442,769 Kenyon June 8, 1948 OTHER REFERENCES Proc. of I. R. E., vol. 28, No. 9, Sept. 1940, Generation of Synchronizing Pulses by Impulse Excitation by Sherman. 

